In the 2021 Census of Population conducted by Statistics Canada, the RM of Three Lakes No. 400 had a population of 725 living in 228 of its 376 total private dwellings, a change of 21.2% from its 2016 population of 598. With a land area of 770.76 km2 (297.59 sq mi), it had a population density of 0.9/km2 (2.4/sq mi) in 2021.[7]
In the 2016 Census of Population, the RM of Three Lakes No. 400 recorded a population of 598 living in 213 of its 340 total private dwellings, a -3.5% change from its 2011 population of 620. With a land area of 772.49 km2 (298.26 sq mi), it had a population density of 0.8/km2 (2.0/sq mi) in 2016.[4]
The RM of Three Lakes No. 400 is governed by an elected municipal council and an appointed administrator that meets on the second Wednesday of every month.[3] The reeve of the RM is Allen Baumann while its administrator is Tim Schmidt.[3] The RM's office is located in Middle Lake.[3]